Embryonic development of Girardia tigrina (Girard, 1850) (Platyhelminthes, Tricladida, Paludicola).

The embryonic development of freshwater triclads is mainly known from studies of species of Dendrocoelum, Planaria, Polycelis, and, more recently, Schmidtea. The present study characterizes the development of Girardia tigrina (Girard, 1850) by means of optical microcopy using glycol methacrylate semi-thin sections. 94 cocoons were collected in the period from laying to hatching, with intervals of up to twenty-four hours.

Cadmium chloride-induced disruption of testicular steroidogenesis in rainbow trout, Oncorhynchus mykiss.

Cadmium (Cd) is a known endocrine disruptor with the ability to affect the production of hormones involved in the regulation of reproductive processes. In the present study, the effects of CdCl(2) on unstimulated and stimulated testicular steroidogenesis were examined with the intention of furthering the understanding of the potential site(s) of action in the signaling pathway for 11-KT synthesis in teleosts. In short-term (2-h) exposures, CdCl(2 )stimulated 11-KT production (29% and 28% over controls) in minced testicular tissues at concentrations of 10 and 100 microM, respectively.

Biosynthetic capacity of rainbow trout (Oncorhynchus mykiss) interrenal tissue after cadmium exposure.

The disruption of endocrine system function in wildlife species, including teleosts, by contaminants such as metals is presently of major environmental concern. Recently, it has been shown that cadmium (Cd) exposure results in significant reductions in corticosteroid secretion by fish interrenal steroidogenic cells, likely through an inhibition of intracellular cortisol synthesis. In the present study, the effects of CdCl(2) on unstimulated and stimulated interrenal steroidogenesis in rainbow trout were examined with the intention of furthering an understanding of the site(s) of Cd toxic action.

Histological processing techniques for the study of Dugesiidae development (Platyhelminthes, Tricladida, Paludicola).

The objective of the present study was to adapt techniques for the histological processing of Dugesiidae cocoons for the study of embryo development. The cocoons were fixed with formalin, SUSA, Bouin or paraformaldehyde/glutaraldehyde and subsequently embedded in Paraplast or glycol methacrylate (Historesin). Paraplast embedding yielded reasonable results only after the cocoon was perforated or fixed for a prolonged period of time using softening techniques with acid solutions.

Ultrastructural alterations in glomerulopathy associated with hydatidosis in sheep.

In the present study we investigated the ultrastructural alterations occurring in the renal glomeruli of sheep with hydatidosis. Renal samples from 39 sheep, 34 with hydatidosis and 5 without parasitosis, were examined by transmission electron microscopy. Additionally, biochemical analysis was performed by determining serum concentrations of creatinine, urea, total protein and albumin.